Assembly language programming and organization of the ibm pc solution

Department Of Computer Science And Engineering

Submitted By

Submitted To

Name: Ashadullah Shawon

Dr. Md. Rabiul Islam

Class : 3rd Year, Odd Semester

Professor

Roll No: 133009

Department Of CSE

Subject: Solution of Exercise Problems

RUET

Course Title: Microprocessor And Assembly Language Course No: CSE 3109

Rajshahi

Chapter 4 8. Write a program to (a) display a "?", (b) read two decimal digits who.se sum "is less than 10, (c) display them and their sum on the next line, with an appropriate message. Sample execution: ?27 THE SUM OF 2 AND 7 IS 9 .model small .stack 100h .data msg db 'THE SUM OF$' msg1 db ' $' msg2 db 'AND$' msg3 db 'IS$' .code main proc mov dl,'?' mov ah,2 int 21h

mov ah,1 int 21h mov bl,al mov ah,1 int 21h

mov cl,al

mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h

; carriage return ;new line

mov ax,@data ;initialize data segmet mov ds,ax lea dx,msg mov ah,9 int 21h

lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,bl int 21h lea dx,msg1 mov ah,9 int 21h lea dx,msg2 mov ah,9 int 21h

lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,cl int 21h

lea dx,msg1 mov ah,9

int 21h

lea dx,msg3 mov ah,9 int 21h lea dx,msg1 mov ah,9 int 21h

add bl,cl ;sum sub bl,48d ;convert to ascii number mov dl,bl mov ah,2 int 21h

mov ah,4ch int 21h

main endp end main

Output:

9.Write a program to (a) prompt the user, (b) read first, middle, and last initials of a person's name, and (c) display them duwn the left margin. Sample execution: ENTER THRl::E INITIALS: JFK J F K

.model small .stack 100h .data msg db 'ENTER THREE INITIALG: $' .code main proc mov ax,@data ;initialize data segment mov ds,ax lea dx,msg mov ah,9 int 21h mov ah,1 int 21h mov bl,al

mov ah,1 int 21h mov cl,al

mov ah,1 int 21h mov bh,al mov ah,2 mov dl,0dh ;caariage return int 21h mov dl,0ah ;new line int 21h

mov ah,2 mov dl,bl int 21h mov dl,0dh int 21h mov dl,0ah int 21h

mov ah,2 mov dl,cl int 21h mov dl,0dh int 21h mov dl,0ah int 21h

mov ah,2 mov dl,bh int 21h mov ah,4ch int 21h main endp end main

Output:

10. Write· a program to read one of the hex digits A-F, and display it on the next line in decimal. Sample execution: ENTER A HEX DIGIT: C IN DECIMAL IT rs 12

.model small .stack 100h .data msg1 db 'Enter a hex digit: $' msg2 db 'In decimal it is: $' .code main proc mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h mov ah,1 int 21h mov bl,al sub bl,17d ; convert to corresponding hex value as C=67. So 67-17=50=’2’

mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg2 mov ah,9 int 21h

mov dl,49d ;print 1 at first mov ah,2 int 21h mov dl,bl mov ah,2 ; print next value of hex after 1 int 21h main endp end main Output:

11. Write a program to display a t 0 x 10 solid box of asterisks. Hint: declare a string in the data segment that specifies the box, and display it with INT 2lh, function 9h.

.model small .stack 100h .data msg1 db '**********$' .code main proc mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h

;print 10 times

mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h lea dx,msg1 mov ah,9 int 21h mov ah,2 mov dl,0dh int 21h mov dl,0ah

int 21h lea dx,msg1 mov ah,9 int 21h mov ah,4ch int 21h main endp end main

Output:

12. Write a program to (a) display"?", (b) read three initials,(cl

9. Write a program to display the extended ASCII characters (ASCJI codes 80h to FF_h). Display 10 characters per line, separated by blanks. Stop after the extended characters have been displayed once. .model small .stack 100h .data .code main proc mov cx,127 ;initialize number of character mov bl,0

print: mov ah,2 inc cx cmp cx,255 ja exit mov dx,cx int 21h mov dx,32d ; giving space int 21h

jmp go

go: inc bl cmp bl,10 ; 10 char per line je nl jmp print

nl: mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h mov bl,0 jmp print exit: Output

10. Write a program that will prompt the user to enter a hex digit

character ("0"· ... "9" or "A" ... "F"), display it on the next line

in decimal, and ask the user i.i he or she wants to do it again. If the user types "y" or "Y", the ·program repeats; If the user types anything else, the program terminates. If the user enters an illegal character, prompt the user to try again. .model small .stack 100h .data msg1 db 10,13,'ENTER A HEX DIGIT:$' msg2 db 10,13,'IN DECIMAL IS IT:$' msg3 db 10,13,'DO YOU WANT TO DO IT AGAIN?$' msg4 db 10,13,'ILLEGAL CHARACTER- ENTER 0-9 OR A-F:$'

.code

again: mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h mov ah,1 int 21h mov bl,al

jmp go

go:

cmp bl,'9' ja hex ;if bl>9 go t hex label

jb num je num

hex: cmp bl,'F' ja illegal ;if bl>F illegal

lea dx,msg2 mov ah,9 int 21h mov dl,49d mov ah,2 int 21h sub bl,17d ; convert to letter mov dl,bl mov ah,2 int 21h jmp inp

inp: lea dx,msg3 mov ah,9 int 21h mov ah,1 int 21h mov cl,al cmp cl,'y' je again cmp cl,'Y'

je again jmp exit

num: cmp bl,'0' jb illegal lea dx,msg2 mov ah,9 int 21h

mov dl,bl mov ah,2 int 21h jmp inp

illegal: lea dx,msg4 mov ah,9 int 21h mov ah,1 int 21h mov bl,al jmp go

exit:

11. Do programming exercise 10, except that if the user fails to enter a hex-digit character In three tries, display a message and terminate the program. .model small .stack 100h .data msg1 db 10,13,'ENTER A HEX DIGIT:$' msg2 db 10,13,'IN DECIMAL IS IT:$' msg3 db 10,13,'DO YOU WANT TO DO IT AGAIN?$' msg4 db 10,13,'ILLEGAL CHARACTER- ENTER 0-9 OR A-F:$' msg5 db 10,13,'Too Many Try$'

.code

again:

mov cx,0 mov ax,@data mov ds,ax lea dx,msg1 mov ah,9

int 21h mov ah,1 int 21h mov bl,al jmp go

go: cmp bl,'9' ja hex jb num je num

hex: cmp bl,'F' ja illegal

lea dx,msg2 mov ah,9 int 21h mov dl,49d mov ah,2 int 21h sub bl,17d mov dl,bl mov ah,2 int 21h jmp inp

inp:

lea dx,msg3 mov ah,9 int 21h mov ah,1 int 21h mov cl,al cmp cl,'y' je again cmp cl,'Y' je again jmp exit

num: cmp bl,'0' jb illegal lea dx,msg2 mov ah,9 int 21h

mov dl,bl mov ah,2 int 21h jmp inp

illegal: inc cx cmp cx,3 je i2 lea dx,msg4 mov ah,9 int 21h mov ah,1

int 21h mov bl,al jmp go

i2: lea dx,msg5 mov ah,9 int 21h jmp exit exit:

Chapter 7 8. Write a program thC!t prompts the user to enter a character, and on subsequent lines prints its ASCII code in binary, and the number of 1 bits In Its ASCII code. Sample execution: TYPE A CHARACTER: A THE ASCII CODE OF A IN BINARY IS 01000001 THE NUMBER OF l BITS IS 2 .model small .stack 100h .data msg1 DB 'TYPE A CHARACTER:$' msg2 DB 0DH,0AH,'THE ASCII CODE OF $' msg3 DB ' IN BINARY IS $' msg4 DB 0DH,0AH,'THE NUMBER OF 1 BITS IS $' .code main proc

mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h mov ah,1 int 21h xor bx,bx mov bl,al lea dx,msg2 mov ah,9 int 21h mov dl,bl

mov ah,2 int 21h lea dx,msg3 mov ah,9 int 21h

mov cx,8 ; limit for loop i8

9. Write a program that prompts the user to enter a character and prints the ASCII code of the character in hex on the next line. Repeat this process until the user types a carriage return. Sample execution: TYPE A CHARACTER: Z THE ASCII CODE OF Z IN HEX IS 5A TYPE A CHARACTER:

.model small .stack 100h .data msg1 db 10,13,'Type a character:$' msg2 db 10,13,'The Ascii code of $' msg3 db ' in hex is:$'

.code main proc

mov ax,@data mov ds,ax

input: lea dx,msg1 mov ah,9 int 21h mov ah,1 int 21h mov bl,al cmp bl,0dh je end lea dx,msg2 mov ah,9 int 21h mov dl,bl mov ah,2 int 21h lea dx,msg3 mov ah,9 int 21h mov cx,4 convert: mov dl,bh shr dl,1 ;shift left 4 times shr dl,1 shr dl,1 shr dl,1 cmp dl,9 jbe num add dl,55d

jmp display num: add dl,30h display: mov ah,2 int 21h rcl bx,1 ;rotate carry left 4 times rcl bx,1 rcl bx,1 rcl bx,1 loop convert

jmp input

end: MOV AH,4CH INT 21H MAIN ENDP END MAIN Output:

10. Write a program that prompts the user to type a hex number of four hex digits or less, and outputs it In binary on the next line. If the user enters an illegal character, he or she should be · prompted to begin again. Accept only uppercase letters. Sample exenitio11: TYPE A HEX NUMBER (0 TO FFFF): la ILLEGAL HEX DIGIT, TRY AGAIN: lABC IN BINAPY IT IS 0001101010111100 .model small .stack 100h .data msg1 db 10,13,' Type a hex number (0 to FFFF):$' msg2 db 10,13,'Illegal hex digit,try again:$' msg3 db 10,13,'In Binary it is $'

.code mov ax,@data mov ds,ax

jmp input invalid: lea dx, msg2 mov ah,9 int 21h

input: lea dx,msg1 mov ah,9 int 21h xor bx,bx mov cl,4 mov ah,1 int 21h

convert: cmp al,0dh je end_input cmp al,'0' jb invalid cmp al,'F' ja invalid cmp al,39h ja letter and al,0fh jmp left

letter: sub al,55d ;convert char to binary left: shl bx,cl or bl,al mov ah,1 int 21h jmp convert

end_input: lea dx,msg3 mov ah,9 int 21h xor dx,dx mov cx,16

print_binary: shl bx,1 ;catch bx bit jc one ;cf=1 mov dl,30h jmp display

one: mov dl,31h display: mov ah,2 int 21h loop print_binary

main endp end main

11. Write a program that.prompts the user to type a binary number of 16 digits or less, and outputs It In hex on the next line. If the user enters an illegal character, he or she should be prompted to begin again . ... . .. ·- -·TYPE A BINARY NUMBER, UP TO 16 DIGITS: 11100001 IN HEX IT IS El .model small .stack 100h .data msg1 db 'Type a binary number upto 16 digits:$' msg2 db 10,13,'in hex it is:$'

.code main proc

mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h xor bx,bx mov ah,1 int 21h

input: cmp al,0dh je exit and al,0fh shl bx,1 or bl,al int 21h jmp input

exit: lea dx,msg2 mov ah,9 int 21h mov cx,4

convert: mov dl,bh shr dl,1 shr dl,1 shr dl,1 shr dl,1 cmp dl,9

jbe num add dl,55d jmp display

num: add dl,30h

display:

mov ah,2 int 21h rcl bx,1 rcl bx,1 rcl bx,1 rcl bx,1

loop convert main endp end main

12. Write a program that prompts the user to enter two.binary numbers of up to 8 digits each, and prints their sum on the next line in binary. If the user enters an illegal character, he or she should be prompted to begin again. Each input ends with a carriage return. TYPE 'A BINARY NUMBER, UP TO 8 DIGITS: 11001010 TYPE 'A BINARY NUMBER, UP TO 8 DIGITS: 10011100 THE BINARY SUM IS 101100110 .model small .stack 100h .data msg1 db 10,13,'Type a binary number upto 8 digits:$' msg2 db 10,13,'The binary sum is:$'

.code main proc

mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h mov ah,1 int 21h xor bx,bx mov cx,8 input1: mov ah,1 int 21h

cmp al,0dh je break and al,0fh ;convert to binary shl bl,1 ;make room for new value or bl,al ;insert value loop input1

break: lea dx,msg1 mov ah,9 int 21h mov cx,8

input2:

mov ah,1 int 21h cmp al,0dh je break2 and al,0fh shl bh,1

;convert to binary ;make room for new value

or bh,al

;insert value

loop input2

break2: lea dx,msg2 mov ah,9 int 21h

sum: add bl,bh ;sum binary 00000011+00000010, bl=000000101 jnc zero ;if sum has no carry then no need to print zero mov dl,31h mov ah,2 int 21h ;if sum has carry 1 then need to print 1

zero: mov dl,30h mov cx,8 print: shl bl,1 ;sending one by onee bit to print 000000101 jnc z mov dl,31h jmp display z: mov dl,30h display: mov ah,2 int 21h loop print main endp end main Output

Chapter 8 8. Write a program that lets the user type s ome text, consisting of words separated by blanks, ending with a carriage return, and displays the text in the same word order as entered, but with the let__,

ters ·in each word reversed. For example, "this is a test" becomes "siht si a tset". .model small .stack 100h .data .code msg1 db 'Enter String:$' msg2 db 'Reverse String:$' count DW 0 main proc mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h

;initialize data segment

xor cx,cx mov ah,1 int 21h input: cmp al,0dh je end_input push ax inc cx int 21h jmp input end_input: mov dx,0dh mov ah,2 int 21h mov dx,0ah mov ah,2 int 21h mov bx,50h xchg bx,sp push 0020h xchg bx,sp

;carriage and new line

;swap sp pointer

inc count loop1: pop dx xchg bx,sp push dx xchg bx,sp inc count

;swap bx and sp ; push to new stack

loop loop1 lea dx, msg2 mov ah,9 int 21h mov cx,count mov count,0 push 0020h inc count

; push 0020H onto the STACK

reverse: xchg bx, sp pop dx xchg bx, sp cmp dl, 20h jne skip

; swap bx and sp ; pop a value from stack into dx ; swap bx and sp

mov ah, 2 loop2: pop dx int 21h dec count jnz loop2 mov dx, 0020h skip: push dx inc count

; pop and show output

loop reverse mov ah, 4ch int 21h main endp end main

10. The following method can be used to generate random numbers in the range 1 to 32767. Start with any number in this range. Shift left once. Replace bit 0 by the XOR of bits 14 and 15. Clear bit 15. Write the following procedures: a. A procedure READ that lcr, and calls RANDOM and WRITE to compute and display 100 random numbers. The numbers should be displayed four per line, with four blanks scparatlng the numbers. .model small

.stack 100h .data msg1 db 'Enter a binary number:$' msg2 db 10,13,'Random numbers are:$' msg3 db 10,13,'illegal entry: try again:$' va dw ? vb dw ? vc dw ? .code main proc mov ax,@data mov ds,ax mov vb,1 call rproc

; mov 1 to word vb ; callling new procedure

mov ah,9 lea dx,msg2 int 21h star: mov vc,1 cmp vb,25 jg las inc vb mov ah,2 mov dl,0ah int 21h start: call random call write mov ah,2 mov dl,' ' int 21h inc vc

; calling random proc

cmp vc,4 jle start jmp star las: mov ah,1 int 21h mov ah,4ch int 21h main endp rproc proc mov ah,9 lea dx,msg1 int 21h soo: mov cl,16 xor bx,bx top: mov ah,1 int 21h cmp al,0dh je last cmp al,'0' jne as jmp asd as: cmp al,'1' jne error asd: and al,0fh shl bx,1 or bl,al loop top jmp last error: mov ah,9 lea dx,msg3

int 21h jmp soo last: ret rproc endp random proc shl bx,1 xor dx,dx mov a,bx mov dx,bx shl va,1 xor dx,a rol dx,1 jc setbx and bx,0fffeh jmp go setbx: or bx,0001h go: ret random endp write proc mov cl,16 top1: rol bx,1 jc one mov ah,2 mov dl,'0'

int 21h jmp en one: mov ah,2 mov dl,'1' int 21h en: loop top1 ret

; returning to procedure

write endp end main

Output:

Chapter 9

8. Modify procedure INDEC so that it will check for overflow. Modified Decimal Input Code (INDEC) For Overflow : indec proc push bx push cx push dx start: mov ah,2 mov dl,0dh int 21h mov dl,0ah int 21h mov ah,2 mov dl,'?' int 21h xor bx,bx ; bx is for total=0 xor cx,cx ; cx is for detecting sign mov ah,1 int 21h cmp al,'-' ; if minus sign set it je min cmp al,'+' ; if plus sign set it je pl jmp convert ; else convert to decimal min: mov cx,1 ; negative is true pl: int 21h convert: cmp al,'0'

jl illegal cmp al,'9' jg illegal and ax,000Fh ; convert ascii char to decimal push ax ; save on stack mov ax,10 ; set value 10 for multiply imul bx ; multiply by 10, ax=total*10 jo of1

; jump if overflow

pop bx ; bx= converted decimal digit add bx,ax ; total=total*10+ decimal digit jo of2 ; jump if overflow mov ah,1 int 21h cmp al,0dh je cr jmp convert cr: mov ax,bx ; move decimal number to ax or cx,cx ; negative sign je exit ; if not negative neg ax exit: pop dx pop cx ;restore registers pop bx ret of1: pop bx mov ah,9 lea dx,msg1 int 21h jmp start

of2: mov ah,9 lea dx,msg1 int 21h jmp start illegal: mov ah,2 mov dl,0ah int 21h jmp start indec endp Decimal Output Code (OutDEC): outdec proc push ax push bx push cx push dx or ax,ax jge valid ; if ax>=0 push ax mov dl,'-' mov ah,2 int 21h pop ax neg ax valid: xor cx,cx mov bx,10d ; bx is divisor

divide: xor dx,dx ; dx is remainder div bx push dx

; divide ax by bx, ax =quotient, dx=remainder ; push remainder

inc cx or ax,ax ; untill ax is not zero jne divide mov ah,2 print: pop dx or dl,30h ;print digits int 21h loop print pop dx pop cx pop bx pop ax ret outdec endp Input And Output Decimal: .model small .stack 100h .data msg1 db 10,13,'Invalid!! Overflow',0AH,'$' .code main proc mov ax,@data mov ds,ax call indec push ax mov ah,2 mov dl,0dh int 21h

mov dl,0ah int 21h pop ax call outdec mov ah,4ch int 21h main endp include outdec.asm include indec.asm end main Output:

9. Write a program that lets the user enter time in seconds, up to 65535, and outputs the time as hours, minutes, and seconds. Use INDEC and OUIDEC to do the 1/0. .model small .stack 100h .data msg1 db 'Enter time in seconds:$' msg2 db 10,13,'Time in Hour Miniute And Second Is:$' .code main proc mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h call indec push ax

xor cx,cx mov cl,3 pop ax l1: xor dx,dx ; dx is remainder mov bx,60d ; bx is divisor div bx ; ax =quotient push dx ; push remainder loop l1 mov ah,9 lea dx,msg2 int 21h mov cl,3 time: pop ax ; get remainder call outdec mov ah,2 mov dl,':' int 21h loop time mov ah,4ch int 21h main endp include outdec.asm include indec.asm end main Output:

12. Write a program to find the greatest common divisor (GCD) of two integers M and N, according to the following algorithm: 1. Divide M by N, getting quotient O and remainder R. 2. If R = 0,. stop. N is the GCD of M and N. 3. If R O, · replace M by N, N by R, and repeat step 1. Use INDEC to enter M and N and OUTDEC to print the GCD. .model small .stack 100h .data msg1 db 'Enter M=$' msg2 db 10,13,'Enter N=$' msg3 db 10,13,'GCD is=$' a dw ? b dw ? .code main proc mov ax,@data mov ds,ax lea dx,msg1 mov ah,9 int 21h

call indec ;input push ax lea dx,msg2 mov ah,9 int 21h call indec push ax xor bx,bx pop bx pop ax cmp ax,bx jl swap jmp gcd swap: mov a,ax mov ax,bx mov bx,a gcd: xor dx,dx mov b,bx div b cmp dx,0 je go mov ax,bx mov bx,dx jmp gcd go: lea dx,msg3 mov ah,9 int 21h mov ax,b call outdec mov ah,4ch int 21h

main endp

;input

; if ax is small then swap

;swap ax and bx

;remainder dx

; if remainder is zero print gcd ; replace divident by divisor ; replace divisor by remainder

;print gcd

include outdec.asm include indec.asm end main

Output:

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